Jenkins's ad slams Rahall as a "lying politician just like Obama," hitting the lawmaker for claims from the House Majority PAC that fact-checkers have questioned, while Rahall's features the president of a national mining union attacking billionaires Charles and David Koch.

"I'm Cecil Roberts, a native West Virginian and a sixth-generation coal miner. It makes me mad when billionaires are spending millions of dollars telling lies about Nick Rahall," the United Mine Workers of America president says in the ad. "Nick is our friend. Nick passed a miner safety act and he's fighting for our jobs, our healthcare and our pension. The big-money special interests want to pick their own congressman. Don't let them do it — stick with Nick."

Jenkins's ad attacks the House Majority PAC, which has been hammering him on the airwaves. The Democratic group accuses Jenkins of wanting to repeal black lung protections, for instance, because he wants to repeal ObamaCare, which includes new protections for the condition.

The ad's second half pivots to Jenkins, whom it describes as having "the backbone to defend our way of life from Obama's war on coal" in the coal-heavy district.

Both campaigns seem to be rushing to put up ads in response to the barrage of negative attacks the outside groups are leveling in the race.